Water-repellent cotton textiles



United States Patent Ofiice 2,802,754 Patented Aug. 13, 1957 WATER-REPELLENT CGTTON TEXTILES I Bruce A. Ashby, Schenectady, and Carroll J; Hoffman,

Saratoga Springs, N. Y., assignors to General Electric Company, a corporation of New York No Drawing. Application October 31, 1956, Serial No. 619,383

8 Claims. (Cl. 117-76) N N H (g g H CHaOCHzN- NCH2OOHa (hereinafter referred to as melamine product), (2') converting the melamine product on the textile material to the substantially insoluble state, (3) treating the textile material obtained in (2) with an alkyl hydrogen polysiloxane containing, by weight, from to 200% thereof, of an alkyl polysiloxane free of silicon-bonded hydrogen, and (4) heating the latter treated textile at a temperature above. 100 C. to effect conversion of the alkyl polysiloxane to the substantially infusible and insoluble state. It has been known heretofore that solid bodies, for instance various textiles, can be rendered water-repellent by treatment with organopolysiloxanes. In addition, as shown in Rasmussen Patent 2,612,482, improvements in water-repellency of textiles. can be obtained by applying to the textiles a combination of (1) an amido resin (e. g for instance, urea formaldehyde resins, melamine-formaldehyde resins, etc.) and (2) a mixture of organopolysiloxanes composed of (a) a methylpolysiloxane and (b) a methyl hydrogen polysiloxane, all in one treating medium, and thereafter heating the treated textile at elevated temperatures to effect conversion ofthe coating thereon to the water-repellent state. Although treatments of textiles, such as wools, rayons, and rayon acetates give good results with the Rasmussen compositions, nevertheless it has been found that when employing the combined mixture of the melamine condensation product with the 'organopolysiloxanes on cotton, the water repellency, even after 1 or 2 launderings, decreases rapidly, so that after the second or third laundering the water-repellency, as evidenced by the spray rating, has dropped to well below 50 and will ordinarily run was low as a zero spray rating. 1 Unexpectedly, we have discovered that we are able to retain the water-repellency of cotton textiles to a remarkable degree, even after several launderings, if, instead of using a one-step process in which both the amido resin and the silicones are used in one treating composition, one employs instead a two-step process in which the cotton textile material is first treated with a specific melamine condensation product more particularly described above, and thereafter is subjected to treatment to an alkyl hydrogen polysiloxane, preferably a combination of an alkyl polysiloxane and an alkyl hydrogen polysiloxane.

'ofifrom 2.0 to 2.25, inclusive.

It was also unexpectedly found that whereas Rasmussen in his patent was able to use urea condensation products, for instance, condensation products of urea and formaldehyde, or melamine condensation products, such as trimethylol melamine, our claimed process did not permit the use of any other amido resin except the fusible, soluble methyl ether derivative of trimethylol melamine recited above. Ureaformaldehyde condensation products or unetherified methylol melamines did not give equivalent spray ratings after laundering as did the compositions containing the specific melamine product recited.

The melamine product having the formula CHaOCHrN-( 3 (ii-NECHzOCH;

N. may be prepared by reacting three mols of formaldehyde with one mole of melamine and then etherifying the methylol groups by reaction of the trimethylol melamine with methanol in the presence of an acid catalyst. This latter material is sold by American CyanamidCompany, Stamford, Connecticut, as M-3 resin or by Monsanto Chemical Company as M- resin. The melamine product is.a water-soluble. materialin the incompletely condensed, state. In the presence of small amounts of curing catalysts, for instance, amine hydrochlorides such as those disclosed in U. S. Patent. 2,467,160, and at temperatures ranging from about 75 to- C., the melamine product can be. condensed to. the substantially infusible and insoluble state.

The alkyl hydrogen polysiloxane employed in the practice of the present invention has the formula II. 0H b 4;-b where R is an alkyl radical, specifically a lower alkyl radical, e. g., methyl, ethyl, propyl, butyl, isopropyl, etc., a has a value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25, and the sum of a and b has a value Such compositions are also known commercially in the literature and may be obtained by hydrolyzing, for instance, methyldichlorosilane alone, or combinations of methyldichlorosilane and trimethylchlorosilane to form chain-stopped linear fluids. Alkyl hydrogen polysiloxanes having viscosities of from 10 to 10,000 centistokes at room temperature, are advantageously used. Methods for making fluids of this type may be.- found disclosedin Norton Patent 2,386,259 and in Sauer Patents 2,595,890 and 2,595,891. These alkyl polysiloxanes containing silicon-bonded hydrogen will hereinafter be referred to as alkyl hydrogen polysiloxane or, more specifically, as methyl hydrogen polysiloxane.

The alkyl polysiloxane free of silicon-bonded hydrogen used in the treating process described above (in amounts ranging from 0 to 200 percent of the weight of the alkyl hydrogen polysiloxane) has the formula where R has the meaning above and n is equal to from about 1.6 to. 1.98. These alkyl polysiloxanes are fluids which have a viscosity of from 10 to 10,000 centistokes at room temperature (about 28 C.). They are well known commercially and may be produced by cohydrolyzing and condensing a mixture of alkyl chlorosilanes, for instance, methylchlorosilanes of the general average formula (CH3)nSlcl4---n Where n has a value of from 1.5 to 1.98. Thus, one may cohydrolyze a mixture composed of methyltrichlorosilane,

dimethyldichlorosilane and trimethylchlorosilane in such molar ratios as will give a methyl-to-silicon ratio of from 1.5 to 1.98. Instead of methyl groups attached to silicon, one may have ethyl groups, mixed methyl and ethyl groups, mixtures of methylchlorosilanes and ethylchlorosilanes, etc. Such compositions will hereinafter be referred to for brevity as alkyl polysiloxanes or, more particularly, as methylpolysiloxanes.

The proportions of the melamine product, the alkyl polysiloxane and the alkyl hydrogen polysiloxane may be 'varied within wide limits without departing from the scope of the invention. Advantageously, on a weight 'basis, the melamine product is employed in about a 0.5

alkyl hydrogen polysiloxane are employed, the former is often advantageously present in an amount less than 100 percent (e. g., from 5 to 75%), by weight, of the two types of polysiloxanes. The alkyl hydrogen polysiloxane 'or the mixture of the alkyl hydrogen polysiloxane and the alkyl polysiloxane may be employed in the form of solutions in organic solvents (e. g., in solids concentrations ranging from about 1 to or percent, by weight) employing solvents such as benzene, xylene, toluene, etc. More advantageously, the alkyl hydrogen polysiloxane alone or the latter in combination with the alkyl polysiloxanes is employed in the form of an aqueous emulsion. In order to prepare emulsions of these polysiloxanes, one can employ various emulsifying agents (preferably those whose emulsifying action is destroyed by heat) as, for instance, such materials as Tetrosan marketed by Onyx Chemical Company and identified as technical alkyl dimethyl-3,4-dichlorobenzyl ammonium chlorides in which the alkyl groups are normal primary aliphatic radicals having from 8 to 18 carbon atoms; stearamine acetate; alkali-metal salts of sulfonted methyl oleate (e. g., Calsolene Oil HSA sold by Arnold Hoffman Co., Providence, Rhode Island); polyoxyethylated fatty acid amides (e. g., Armour and Companys Ethomids), etc. It will, of course, be apparent to those skilled in the art that any other suitable emulsifying agent may be employed without departing from the scope of the invention.

One general method for making the emulsions of the polysiloxanes is to mix the polysiloxane and the emulsifying agent with water and eifect emulsification by thoroughly agitating the combination of ingredients until a homogeneous emulsion is formed. This latter emulsion may be obtained in dilute or concentrated forms and, if

in a concentrated form, may be further diluted to give an emulsion in which, by weight, from 1 to 30 percent of the emulsion is the alkyl hydrogen polysiloxane or mixture of polysiloxanes.

In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation. All parts are by weight.

EXAMPLE 1 The melamine condensation product employed in this example was the above described M3 melamine condensation product sold by American Cyanamid and was in the form of a 5 percent solids aqueous solution containing 1 percent, by weight, of the melamine product, 'of an acidic catalyst, specifically 2-methyl-2-amino-1- hydroxypropane hydrochloride.

The organopolysiloxane treating mixture was in the 2,802,754 ,7 V .r 'l g form of an aqueous emulsion containing 2 percent, by weight, thereof of a mixture of a methylpolysiloxane and a methyl hydrogen polysiloxane. The methyl polysiloxane was obtained by cohydrolyzing about 5 parts trimethylchlorosilane, 161 parts dimethyldichlorosilane and about 48 parts of methyltrichlorosilane. The methyl hydrogen polysiloxane was obtained by cohydrolyzing parts methyldichlorosilane and 5 parts trimethylchlorosilane. These materials were mixed in an equal weight ratio and emulsified with water and an emulsifying agent (Calsolene Oil HSA sold by Arnold Hofiman) to give a 2 percent solids solution. Also added to this emulsion was a catalyst for the mixture of polysiloxanes, specifically stannous oleate, in such amount that there was present about 10 percent tin as stannous oleate, based on the total weight of the methyl polysiloxane and methyl hydrogen polysiloxane.

The test to determine the durability of the water-repellency after successive washing cycles was carried out as follows. After treatment of the cotton cloth with either the two-step procedure described above or by means of a control in which the melamine condensation product was incorporated in a single emulsion with the methylpolysiloxane and methyl hydrogen polysiloxane, the treated cotton samples were subjected to a wash cycle in a closed quart jar containing 400 ml. of water, of which 0.5 percent thereof was Lux soap powder. Agitation in this Lux mixture was carried out for about 90 minutes at about 75 C. Thereafter, the treated textile was rinsed three times with warm water and then ovendried for 5 minutes at C. at which time the waterrepellency was tested in accordance with a water spray test using the method set forth in the 1945 Yearbook of the American Association of Textile Chemists and Colorists, volume 22, pages 229 to 233.

In the two-step treatment, the cotton textile after treatment with the melamine product was dried and cured in one operation by heating 5 minutes at 110 C. Thereafter, the textile was passed through the organopolysiloxane emulsions and again heated for 5 minutes at 110 C. and then 5 minutes at C. In the one-step treatment, the treated textile cloth was subjected to a single heat treatment for 5 minutes at 110 C. and then for 5 minutes at 150 C. The following Table I shows the results of the various spray tests in which the onestep and two-step operations were employed.

Table I Spray Ratings after Initial stipulated Wash Cycles Treatment Spray Rating One-step 100 80 50 0 0 Two-step 100 90 80 80 70 .of 80 after the third wash, and a spray rating of 70 after the fourth laundering.

EXAMPLE 2 In this example, a two-step treatment was applied to cotton cloth similarly as was done in Example 1 with the exception that instead of employing equal parts, by weight, of the methyl polysiloxane and methyl hydrogen polysiloxane, the methyl hydrogen polysiloxane comprised 20 percent of the total weight of the latter and the methyl polysiloxane described in Example 1. Also, the melamine condensation product was in the form of a 4 percent solidsaqueous solution, either alone or when used in the emulsion of the polysiloxanes. Cotton cloth, both mercerized and unmercerized, was treated with a mixture of the melamineproduct and the above combination of methyl polysiloxane .and methyl hydrogen polysiloxane. The same treating techniques were employed in this example for the cotton samples as were used in connection with the cotton samples of Example 1. As a result of these treatments, it was found that the two-step treatment on both mercerized and unmercerized cotton cloth gave spray ratings of about 80 to 90 even after two launderings. In contrast to this, the one-step treatment resulted in a spray rating after the first laundering of between 70 and 80 and after the second laundering had droppedto 50 on both the mercerized and unmercerized samples. 7

EXAMPLE 3 In this example, .amethyl hydrogen polysiloxanechainstopped. with trimethylsilyl groups was prepared by cohydrolyzing 95 parts methyldichlorosilane and 5 parts trimethylchlorosilane in the manner described in the above-mentioned Sauer Patent 2,595,890. This fluid methyl hydrogen polysiloxane was formed into an aqueous emulsion containing 2 percent, by weight, of the methyl hydrogen polysiloxane employing the same procedure for making the emulsion as described in Exarnple l. A 4 percent solids aqueous solution of the melamine product described above was also prepared. Finally, an aqueous emulsion was made similarly as in Example 1 containing, by weight, 2 percent of the methyl hydrogen polysiloxane and 4 percent of the melamine product, this being in the form of a single emulsion. Both mercerized and unmercerized cotton samples were treated with the one-step procedure (employing the single emulsion of the melamine product and the methyl hydrogen polysiloxane) and the two-step procedure (employing, first, treatment with the melamine product solution, and thereafter treatment with the aqueous emulsion of the methyl hydrogen polysiloxane) employing the same ingredients and procedures, for instance, concentrations, time, temperature, catalysts, etc., as recited in Example 1. As a result of these treatments, it was found that although the mercerized and unmercerized cotton had initial spray ratings of 100, after treatment with the two-step procedures, both the mercerized and unmercerized cotton had spray ratings ranging from 70 to 80 even after three washings. In contrast to this, the unmercerized cotton treated in the one-step method had a spray rating of 0 after the first laundering while the mercerized cotton had a spray rating of 50 after the third laundering.

It will, of course, be apparent to those skilled in the art that instead of using the methylpolysiloxane and methyl hydrogen polysiloxane described in the foregoing examples, other alkyl polysiloxanes and alkyl hydrogen polysiloxanes, many examples of which are apparent from the above disclosures and from the prior art, may be used without departing from the scope of the invention. Also, the proportions of ingredients may be varied widely as well as the treating conditions including the methods for applying the melamine product and the alkyl polysiloxane and the alkyl hydrogen polysiloxane. Instead of employing an emulsion of the ingredients recited previously, it is also possible to use a solution of the ingredients, for instance, to use an organic solvent which is a solvent for both the alkyl polysiloxane and the alkyl hydrogen polysiloxane.

By means of our invention, it is possible to obtain cotton textiles which are water-repellent and have good spray resistance initially and are able to maintain the spray resistance values even after repeated launderings.

It shouldxbe noted that the order of applying the ingredients, namely, first the melamine product and thereafter the alkyl hydrogen polysiloxanes or mixture of polysiloxanes, is critical, and a reversal of the order of application will not give the same results.

The term cotton or cotton textile as used in the specification and claims is intended to include within its scope the usual cotton materials (including mercerized or unmercerized cottons) as well as acetylated cotton (obtained, for instance, by treatment of cotton with glacial acetic acid, acetic anhydride, etc.) as well as cyanoethylated cotton, (obtained, for instance, by treating cotton with acrylonitrile in the presence of caustic, for instance, as is more particularly described in U. S. Patent 2,724,632 issued November 22, 1955).

We claim:

l. The process for improving the ability of cotton textile to retain its 'water-repellency after laundering which comprises (.1) treating-the cotton textile with a melamine product having the formula H C-NCHaOCHs (2) converting the melamine product on the cotton to the substantially insoluble state, (3) applying to the treated textile of (2) an alkyl hydrogen polysiloxane having the formula where R is an alkyl radical, a has a value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25 and the sum of a and b has a value of from 2 to 2.25, inclusive, and (4) heating the latter treated textile at a temperature in excess of C. to elfect conversion of the alkyl polysiloxane to the substantially cured state.

2. The process as in claim 1 in which R in the alkyl hydrogen polysiloxane is a methyl group.

3. The process for improving the ability of cotton textile to retain its water-repellency after laundering which comprises (1) treating the cotton textile with a melamine product having the formula H H H omoomN-o CNCHzOCHa (2) converting the melamine product on the cotton to the substantially insoluble state, (3) applying to the treated cotton textile a mixture of polysiloxanes composed of (a) an alkyl hydrogen polysiloxane having the formula and (b) an alkyl polysiloxane free of silicon-bonded hydrogen having the formula where R is an alkyl radical, a has a value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25 and the sum of a and b has a value of from 2.0 to 2.25, inclusive, and n is a value equal to from 1.5 to 1.98, and (4) heating the latter treated textile at a temperature in excess of 100 C. to efiect conversion of the polysiloxanes to the substantially cured and water-repellent state.

4. The process as in claim 3 in which R is a methyl group.

5. The process as in claim 2 in which the methyl hydrogen polysiloxane is in the form of an aqueous emulsion.

6. The process for improving the ability of cotton textile to retain its water-repellency after laundering which 7 comprises 1) treating the cotton textile with a dilute aqueous solution of a melamine product having the formula and (b) from 5 to 75 percent of an alkyl polysiloxane free of silicon-bonded hydrogen having the formula where R is an alkyl radical, a has a value of from 1.0 to

1.5, b has a value of from 0.75 to 1.25, and the sum of a and b has a value of from 2.0 to 2.25, inclusive, and n is a value equal to from 1.5 to 1.98, there being incorporated in the aqueous emulsion a metallic salt curing agent for the two polysiloxanes, and (4) heating the latter treated cotton textile at a temperature in excess of C. to effect conversion of the polysiloxanes to the substantially cured and water-repellent state.

7. Cotton textile having improved water-repellency after laundering obtained in accordance with the process described in claim 1.

8. Cotton textile having improved water-repellency after laundering obtained in accordance with the process described in claim 3.

References Cited in the file of this patent UNITED STATES PATENTS 2,339,203 Stiegler et al Jan. 11, 1944 2,386,259 Norton Oct. 9, 1945 2,546,575 Wooding Mar. 27, 1951 2,575,443 Cornwell Nov. 20, 1951 2,612,482 Rasmussen Sept. 30, 1952 

1. THE PROCESS FOR IMPROVING THE ABILITY OF COTTON TEXTILE TO RETAIN ITS WATER-REPELLENCY AFTER LAUNDERING WHICH COMPRISES (1) TREATING THE COTTON TEXTILE WITH A MELAMINE PRODUCT HAVING A FORMULA 